Thanks for your reply.
I'm 34 and I've always exercised 3-5 times a week. I usually walk on the treadmill but have just started the interval running.
I have the treadmill on a very slight incline of about 3 and my running shoes are about 4 months old. By the time I get to the treadmill I've already rowed 2000 metres and lifted light weights for about 20 mins. I also ALWAYS stretch thoroughly after every session for about 20 mins.
The area concerned is near the joint line and I'm now getting some aching behind the knees.
The twisting pain occurs whether my leg is straight or bent.
I've had painful knees before but that was due to a lower back and pelvic problem and the pain was completely different.
I don't play any sport at all but occasionally I cycle, altough not since the summer.
I don't have any loss of sensation but when I get out of bed I have pain on the outer edge of my right foot. I put this down to the fact I'm not walking properly due to the knees.
I'm not training at the moment because it's too painful and the pain is constant even when resting.